JP 2007-032589A discloses a control valve apparatus of a power shovel. In the control valve apparatus of the power shovel, a valve block includes a first pump port connected to a first pump and a second pump port connected to a second pump. In addition, the valve block includes a first hydraulic circuit system communicating with the first pump port and a second hydraulic circuit system communicating with the second pump port.
The first hydraulic circuit system is provided with a travel control valve that controls one of travel motors and a plurality of working control valves sequentially from the upstream side. The second hydraulic circuit system is provided with a straight-travel valve, a travel control valve that controls the other travel motor, and a plurality of working control valves sequentially from the upstream side.
The first hydraulic circuit system is provided with a supply channel connected to the first pump port and a neutral flow path that causes the supply channel to communicate with a tank port in a case where each control valve is in a neutral position. The supply channel is connected to a flow-dividing channel in the upstream side of the travel control valve. This flow-dividing channel is connected to the straight-travel valve of the second hydraulic circuit system. The supply channel connected to the second pump port is connected to the straight-travel valve.
When the straight-travel valve is in a normal position, the flow-dividing channel communicates with a parallel channel of the first hydraulic circuit system via the straight-travel valve. Each of the working control valves is connected in parallel via the parallel channel. The parallel channel communicates with the neutral flow path through a branching channel connected to the upstream side of the working control valve.
The second hydraulic circuit system is provided with a supply channel connected to the second pump port and a neutral flow path that causes the supply channel to communicate with a tank port in a case where each control valve is in a neutral position. The supply channel is connected to a parallel channel in the upstream side of the straight-travel valve. Each of the working control valves is connected in parallel via the parallel channel.
In a case where the straight-travel valve is in a normal position, the second pump port communicates with the neutral flow path provided in the downstream side of the straight-travel valve.
If the straight-travel valve switches to a switching position, the travel control valve of the first hydraulic circuit system and the travel control valve of the second hydraulic circuit system connected via the straight-travel valve are connected to the first pump port in parallel. Meanwhile, each parallel channel of the first and second hydraulic circuit systems is connected to the second pump port in parallel.